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Old 12-15-2010, 12:49 PM   #1
1-3-2-4
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Default Will a JDM EJ20 work in place of an EJ25?

Forgive the crappy wording of that question, but this sums it up. I have an EJ25 engine in my Forester that needs replacement due to a REALLY long story. However, I can get a JDM EJ20 which I'm told is a direct swap. Supposedly, the intake and exhaust will swap over from my EJ25, but I want to hear feedback on everything else. Namely, if my sensors and harness swap nicely, will the ECM still scale the fueling/timing accordingly for the reduced displacement? I'm told it will, but I need more than a rumor to move forward.

Thanks!
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Old 12-15-2010, 01:41 PM   #2
BAN SUVS
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No, it's not direct swap. Even if it was, you'd have maybe 110 hp after swapping in a small displacement low compression motor. You can get a replacement motor for your car at a recycler for a relatively decent price.
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Old 12-15-2010, 02:33 PM   #3
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Yeah dont swap down your EJ252/3/4 already lacks in power the EJ20 will be much worse.
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Old 12-15-2010, 03:12 PM   #4
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If you have any good leads, let me know. I'm told the EJ20 is 155 hp, which isn't much lower than my stock 165. Not sure about torque curve, though. If you're looking for more back story, see here: http://www.subaruforester.org/vbulle...houghts-83463/
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Old 12-15-2010, 04:01 PM   #5
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i was going to ask the same question. my buddy can't find a cheap ej25D and needs atleast 500 even to put his heads and motor back together let alone the other junk to put it back in completely and i got a ej20 longblock in my garage. his daily type-R swapped LS teg is eating what is technically his 4th trans in 1.5yr (3-TypeR rebuilds and LS trans).

Were only worried if it'll be driveable for a while so he can figure things out with a different car or atleast part out the type-R swapped teg and buy something else.
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Old 12-15-2010, 04:27 PM   #6
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Is the jdm engine sohc or dohc? You would need a phase 2 sohc jdm EJ20 n/a to swap into your 99 forester. The phase 1 EJ20 dohc n/a engine won't work.
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Old 12-15-2010, 04:59 PM   #7
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This is a N/A EJ20 SOHC....just like my EJ25.

My main concern is fueling. I'm sure I can make everything else work. IF the ecu can adapt during closed loop, great! But, what about the open loop areas like idle and WOT? I don't want to foul plugs, have hard starting, poor (relative) fuel economy, etc.
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Old 12-15-2010, 05:21 PM   #8
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Since the 99 forester is maf based it should be able to compensate. A map car might not.

I've never tried the swap you are contemplating, but I have done a ton of EJ25D to EJ22 swap using the EJ25D ecu and they all ran normally.
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Old 12-15-2010, 05:27 PM   #9
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Quote:
Originally Posted by 69subaru360 View Post
Since the 99 forester is maf based it should be able to compensate. A map car might not.

I've never tried the swap you are contemplating, but I have done a ton of EJ25D to EJ22 swap using the EJ25D ecu and they all ran normally.
Good to know. This is my primary concern. If the closed loop areas aren't significantly different (not saying they are or aren't...), this should be feasible.
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Old 12-15-2010, 08:39 PM   #10
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I still don't see a good reason to buy a JDM engine with 20% less torque with no avenues for returns/exchanges if it doesn't work right. Have you looked for a SOHC EJ25 locally? Literally any from '99 to '05 from Forester, Impreza or Legacy (except the PZEV model) will drop in. Can you really save enough cash to make it worth buying an older engine with way less torque?
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Old 12-15-2010, 09:06 PM   #11
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The premise for this engine is that the engine rebuilder would take back the engine he gave me (which needs work right now) and refund money. He has a 6 month/unlimited mileage warranty - but take that for what it's worth. Incidentally, I'm not crazy about this option, but I'm evaluating it nonetheless. This is a beater car who's project has gone on for long enough. Not looking for power numbers...

I haven't found any running EJ25's locally for sale, but admittedly, I haven't looked since I purchased the rebuilt engine back in November. The ones I did find all needed a full rebuild like mine.
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Old 12-16-2010, 05:55 PM   #12
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How long of a story can an engine failure possibly be?
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Old 12-16-2010, 08:59 PM   #13
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Old 12-13-2016, 04:19 PM   #14
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I know this is old af but dont swap your engine for one that is not sold in your country because of parts. there is virtually no information on this engine like I wanted to order valve springs for the engine was was supposed to be saving me money but I had to have the springs custom made it was a nightmare.
the swap can be done easily
but do your self a favor and just buy a new used block with all the pistons and such
i just wish someone had told me this before I did the swap
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Old 12-14-2016, 11:52 AM   #15
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Quote:
Originally Posted by BAN SUVS View Post
I still don't see a good reason to buy a JDM engine with 20% less torque with no avenues for returns/exchanges if it doesn't work right. Have you looked for a SOHC EJ25 locally? Literally any from '99 to '05 from Forester, Impreza or Legacy (except the PZEV model) will drop in. Can you really save enough cash to make it worth buying an older engine with way less torque?
I thought the early PZEV cars were just additional cats, what makes them not compatible with non PZEV cars?
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Old 12-16-2016, 08:54 PM   #16
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Quote:
Originally Posted by lpxltt View Post
I thought the early PZEV cars were just additional cats, what makes them not compatible with non PZEV cars?
2004 - 2005 2.5 SOHC PZEV engines had a single oval exhaust port in each head.
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Old 12-18-2016, 10:00 AM   #17
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Jlawley,

You haven't responded to the other thread - what did you or did you not do to cause the valve guides to drop?

I'm already in the middle of the swap, so anything I can do to mitigate any issues would be helpful.
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Old 09-12-2020, 06:28 PM   #18
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Default Ej25 to a ej20

I'm in the middle of a eJ25 to a ej20. I have a 2009 impreza sedan. I heard if I leave the cam solenoids off itll still work just cause a check engine light. I hope this works
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